Xiao Tangli, Guan Xu, Nie Ling, Wang Song, Sun Lei, He Ting, Huang Yunjian, Zhang Jingbo, Yang Ke, Wang Junping, Zhao Jinghong
Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, People's Republic of China.
Mol Cell Biochem. 2014 Sep;394(1-2):145-54. doi: 10.1007/s11010-014-2090-7. Epub 2014 May 22.
The aim was to explore the effects of rapamycin on autophagy and injury of podocytes in streptozocin (STZ)-induced type 1 diabetic mice, and its role in delaying progression of diabetic nephropathy. In this study, male Balb/c mice were divided into three groups: control (n = 12), STZ-induced diabetic (n = 12), and rapamycin-treated diabetic (DM + Rapa) (n = 12), which received intraperitoneal injection of rapamycin (2 mg/kg/48 h) after induction of DM. Levels of urinary albumin (UA), blood urea nitrogen, serum creatinine, and kidney weight/body weight were measured at week 12. Renal pathologic changes, number of podocytes autophagy, and organelles injury were investigated by PAS staining, transmission electron microscopy, and immunofluorescence staining, respectively. Western blot was performed to determine the expression of LC3 (a podocyte autophagy marker), phosphorylated mammalian target of rapamycin, p-p70S6K, bax, and caspase-3 protein. Podocytes count was evaluated by immunofluorescence staining and Wilms tumor 1 immunohistochemistry, and Western blot of nephrin and podocin. The results indicated that rapamycin could reduce the kidney weight/body weight and UA secretion. It could alleviate podocyte foot process fusion, glomerular basement membrane thickening, and matrix accumulation, and increase the number of autophagosomes, and LC3-expressing podocytes. Down-regulation of bax and caspase-3 protein, and up-regulation of nephrin and podocin protein were observed in the glomeruli of diabetic mice after administration of rapamycin. In conclusion, rapamycin can ameliorate renal injury in diabetic mice by increasing the autophagy activity and inhibition of apoptosis of podocytes.
目的是探讨雷帕霉素对链脲佐菌素（STZ）诱导的1型糖尿病小鼠足细胞自噬和损伤的影响，及其在延缓糖尿病肾病进展中的作用。在本研究中，雄性Balb/c小鼠分为三组：对照组（n = 12）、STZ诱导的糖尿病组（n = 12）和雷帕霉素治疗的糖尿病组（DM + Rapa）（n = 12），糖尿病诱导后腹腔注射雷帕霉素（2 mg/kg/48 h）。在第12周测量尿白蛋白（UA）、血尿素氮、血清肌酐水平以及肾重/体重。分别通过PAS染色、透射电子显微镜和免疫荧光染色研究肾脏病理变化、足细胞自噬数量和细胞器损伤。进行蛋白质免疫印迹法以测定LC3（足细胞自噬标志物）、磷酸化雷帕霉素靶蛋白、p-p70S6K、bax和caspase-3蛋白的表达。通过免疫荧光染色和肾母细胞瘤1免疫组织化学以及nephrin和podocin的蛋白质免疫印迹法评估足细胞计数。结果表明，雷帕霉素可降低肾重/体重和UA分泌。它可减轻足细胞足突融合、肾小球基底膜增厚和基质积聚，并增加自噬体数量以及表达LC3的足细胞数量。给予雷帕霉素后，糖尿病小鼠肾小球中观察到bax和caspase-3蛋白下调，nephrin和podocin蛋白上调。总之，雷帕霉素可通过增加自噬活性和抑制足细胞凋亡来改善糖尿病小鼠的肾损伤。
